Nice but I wouldn't count on it. That's highly unusual unless you were there for a month. Anyone who expects this is in for a rude awakening.
Even though I eat less and walk a good 10 miles per day at Disney, I GAIN weight temporarily, for several reasons.
I normally eat low carb. When I increase my carbs by any amount, I GAIN 2-3 pounds overnight. If you've been eating low carb, you might experience the same.
The heat and extra sodium cause me to retain fluid, which is good for a few pounds.
Increasing my exercise level by such a significant amount damages muscles and ALSO causes temporary water weight gain; damaged muscles hold fluid to heal themselves.
I'm over 60, which can impact weight gain and loss. I also have more problems than most with fluid imbalances. So YMMV. But I normally gain around 5-6 pounds in a week, not just at Disney, but any time I change my eating pattern.
Just wanted to give a realistic picture to whether or not you might lose weight. Walking burns far fewer calories than you think it does. Walking steadily for 3 full hours at 2 mph(a fairly slow pace) burns about 580 calories if you weigh 150 pounds. The trouble is, most of us stop and start when walking at Disney--we don't walk continuously.